Donall, I don't think Owen was being rude to you, at least not in his first post, but was only expressing his exasperation at such an intriguing but vague request. Do check out the source he mentions, and also John Moulden's booklet 'Thousands Are Sailing' if you can get hold of it. I'm away from home so I can't check it myself. However a bit of Googling for "American Wakes Donegal" suggests that Mici Mac Gabhann's autobiography 'Rotha Mor an tSaoil' contains an account of a Donegal American wake, and that there are more accounts to be found in the writings of the brothers Seosamh and Seamus Mac Grianna. There is a copy of a description of an American Wake by Seamus Mac Grianna, but nothing to say where it comes from.

I don't think there was any particular pattern to emigration ceremonies, involving any specific songs poems or customs until quite late into the 19th century when the practice of the "American wake" evolved. I'd expect songs of blessing or parting to have been used, but the songs you mention are very much songs of exile composed from the Irish-American perspective. I have seen an unsubstantiated claim that 'The Parting Glass' was a song at American wakes, but it seems more likely that it was simply a well-known song that could be pressed into service on such an occasion.

Matthew